Understanding flash duration & ganging Speedlights

<p>I'm getting more and more into action sports photography but am having a hard time deciding which way to go with my lighting. I have several options at my disposal already:</p>

<p>2x Nikon SB-800 with a Quantum 2x2 battery. Very fast recycle, light weight, weak.<br>

1x Quantum Qpaq-X 400ws pack. No heads yet.<br>

3x Alien Bees B800, 1x Alien Bees B1600, 1x Vagabond 2 battery pack. Powerful, heavy.</p>

<p>The Alien Bees do quite well for most of my shoots around town but they are bulky and heavy when using the Vagabond. As I start to go into the snowboarding season, I'll need something lighter and more compact for carrying in a backpack. I have this Quantum pack I scored a great deal on but I've heard the flash durations are pretty weak on their heads. Thinking of selling it. Finally, I have the SB-800's which are awesome for for being so compact, light, and fast to recycle but are weak on power.</p>

<p>Here's my question: How do I multiply watt-seconds when ganging multiple flashes together? I want to determine how many speed-lights I'll need to add to get the same kind of power I'd get from my B800 or B1600 monolights. I also want to know how many I'd need to compare to the Q-flash when powered down enough to reach the desired flash durations (about 1/4 power).</p>

<p>Any other experience or suggestions as to my path would be most welcome.<br>

Thanks,<br>

Sean</p>

<p>What camera and lenses are you using? A camera that can shoot cleanly at, say, ISO 3200, will give you the equivalent of a camera that shoots well at ISO 800 but with much more massive flash helping out. Between a higher ISO and wider lens aperture, you might be able to take advantage of strobe power that's a small fraction of what you'd otherwise need.<br /><br />Or... is this about overpowering sunlight?</p>

<p>Sean,</p>

 

<p>The short version is that you can’t. Even with two different flashes consuming the exact

same amount electricity… the electronics will be more or less efficient, the reflector will be

more or less directional, <i>etc.</i></p>

 

<p>And that’s before you add any sort of modifier to the setup.</p>

 

<p>And <em>that’s</em> assuming that all manufacturers measure the energy

consumption / output of the flashes the same way, and it’s well known that that’s

simply not the case.</p>

 

<p>The best you can do is to actually measure the setup. You can, of course, do this with a flash

meter, but you can also do it pretty easily with a digital camera. Light a gray card with flash, and

keep adjusting the lights until you get a standard exposure. Eventually you’ll figure out that

(for example) the SB-800 at full power illuminates the subject about as well as a B1600 at 1/16

power (or whatever).</p>

 

<p>Cheers,</p>

 

<p>b&</p>

<p>Thanks. I'm using the D700 with 2.8 zooms. Sometimes I will be competing with the sun and have found the Speedlights to be not enough. Ben, I guess I'll have to try that- thanks for the tip!</p>

<p>Consider a battery pack flash such as the Elinchrom Ranger with one of their "A" series heads. Very short flash duration, very powerful and rugged build quality. It's often used for outdoor action sports and snowsports. It's probably the equivalent of 8 SB800's in terms of power. The SB800 flash duration at full power is about 1/1000, whereas the A head on the Ranger has a duration of 1/2300 or higher.</p>